Longitudinal census data from 1980, of the Norwegian population aged 20–64 years, was used to examine the relationship between intragenerational social mobility (as measured by changes in occupational group) and social inequalities in health (as measured by the standardized mortality ratio, SMR). Three propositions were derived from a theoretical model of health selection. In particular, among men the patterns of mobility turned out as expected, e.g. on aggregate those climbing up had a lower mortality than those drifting down, while ‘stayers’ had a lower mortality than those who moved downwards, but a higher mortality than those who moved upwards. Among men, the mobility enhanced the resultant inequality in mortality (as measured by variation coefficients) moderately, i.e. by 8.8%, due to the impact of one occupational group; low salary employees. Among women, although some mobility is in agreement with the propositions, it did not affect the resultant mortality differentials consistently. This evidence lends support to the health selection hypothesis for men, but not for women. Nevertheless, due to the modest selection effect, it may be more fruitful to focus on social and behavioural factors in order to improve the health status of disadvantaged groups, who are the first target of the World Health Organization's strategy for ‘Health for All by the Year 2000’.